Now part of the Apryse family, iText is one of the best-documented and most versatile PDF SDKs in the world.
The open-source iText Core library features a powerful layout engine and intuitive high-level APIs for document creation and manipulation, digital signing and validation, and much more. It has built-in support for PDF 2.0, all variants of PDF/A and PDF/UA, FIPS-140-2 and the very latest ISO standards for digital signatures and encryption.
You can extend iText's capabilities even further, with add-ons for comprehensive HTML/XML and CSS templating, global language and writing systems, secure document redaction, OCR, document optimization, and working with dynamic XFA.
iText Core is free to use under the AGPLv3 license, while a commercial license releases you from the AGPL terms and gives you professional support and maintenance.
Visit the iText website at https://itextpdf.com/ to try the entire iText Suite free for 30 days, while keeping your IP safe under iText's commercial license terms.